The present invention relates to a cable connector for electrical connections, especially for plug-in couplings of electrical cable connections in underground mining, with a connector shell of metal, which has a cable entry opening provided with an internal thread and an abutment collar or engaging portion for a plug connector of plastics material, which is equipped with plug pins and/or sockets, which are joined to the cable conductors of a single or multi-connector cable, preferably provided with screening or armouring. A preferred area of application is the electrical connection of cable connectors, e.g. to electro-hydraulic support controllers. The present invention is not, however, restricted to underground applications.
Cable connectors of the construction previously mentioned with a connector shell of metal, which have a cable entry provided with an internal thread and an abutment seal for a plug connector of plastics material, which is equipped with plug pins and/or sockets which are joined to the cable wires of a single or multiple core electrical cable, are sold by the assignee. The axial retention of the cable in the connector shell is effected by means of a screw connection of plastics material, which is screwed into the cable entry opening with a threaded plug at one end and at its other end has a compression crown arranged in the form of a ring around the cable, which is clamped by means of a cap onto a sealing sleeve surrounding the outer covering of the cable. The cable side seal of the connector part against moisture depends on the clamping force applied to the sealing sleeve, whereby the compression crown and the gap between the individual teeth forms a weak point for the sealing. For application in plug-in connections the cable connectors are plugged into a socket part and secured to this using a captive coupling ring, whereby a sealing element such as an O-ring is arranged between the socket part and the plug-in cable connector as a protection against the ingress of moisture and/or dirt.
The plug-in cable connectors have however been shown not always to be sufficiently watertight in long term application in wet surroundings and in regions in danger from sprayed water, such as especially exist in underground mining operations. The screwed connections with a compression crown are expensive technically in production. Cable connectors provided with screw connections are therefore economically non-competitive owing to their high price. Apart from this, the known cable connectors lack earthing.
It is an aim of the invention to avoid the disadvantages in cable connectors for electrical plug-in connections and by simple means to produce a cable connector suitable for long term application in wet surroundings, such as the water spray regions in underground mining.
Accordingly, the present invention is directed to a cable plug connector as described in the opening paragraph of the present specification, in which a multiple cornered part of metal provided with a through boring for the cable is screwed into the cable entry opening and the cable is fastened in a sealing manner, by means of a formed part formed on the cable covering, to the connector shell and to the multiple cornered part. By the conformation of a suitably formed part an extremely high protection against the ingress of moisture into the interior of the plug shell is produced. The advantages of the formed part comprise inter alia that it caters to a certain extent as a sealing body for the sealing of the cable to the plug shell and the cable entry opening. Since sealing imperfections owing to assembly deficiencies are excluded, quality control of the plug according to the invention can also be performed during the production of the plug-in connector, i.e. immediately following the conformation of the formed part from permanently elastic material. The multiple cornered part of metal, which touches the metal connector shell at the thread surfaces, effects at the same time a secure earthing of the cable.
Preferably the multiple cornered part is provided with threaded sections on its corner edges, so that the flat sides between the comer edges remain of flat construction. With the multiple cornered part screwed in several hollow spaces arise between the outer surface of the multiple edged part and the inner surface of the cable entry opening, into which cast masses of the formed part can penetrate. Preferably the through boring of the multiple cornered part has an indentation, whereby preferably the cable side boring section has a boring diameter which is larger than the diameter of the cable covering. In the intervening space thus created between the cable covering and the multiple cornered part the armouring or screening of the cable, which is turned back over the cable end when the conductor wires are exposed, can be laid in, so that here also the earthing of the cable to the cable connector is ensured.
Advantageously, a clamping sleeve is pushed into the cable side boring section. It is especially favourable then if the exposed armouring or screening of the cable is accepted between the cable side boring section of the multiple cornered part and the clamping sleeve. In a preferred embodiment during assembly the clamping sleeve is retained on the cable covering by a fixing band prior to the forming of the formed part.
Preferably also the length of the multiple cornered part is some 3 to 7 mm longer than the internal thread in the cable entry opening and/or the thread extends only over the cable side partial section of the cable entry opening, so that the multiple cornered part can be screwed self-locking into the cable entry opening. Since the multiple cornered part is longer than the thread, a narrow section of the multiple cornered part extends out of the connector shell, onto which a tool such as for instance a spanner can be applied for the final assembly. Advantageously, the multiple cornered part is a four cornered part.
Preferably, the formed part, is formed as a single part by a suitable plastics material, which material extends in the inside of the connector shell between the internal thread, the flat sides of the multiple cornered part and into the end of the boring and its larger end section outside the connector shell. By a suitable arrangement and conformation of the formed part all the cable side connection gaps between the inner space of the connector shell and its outside are sealed and also the hollow space between the connector shell and the multiple cornered part are filled, so that good sealing is achieved.
In a preferred embodiment a sealing ring encircling the cable covering is enclosed in a section of the formed part extending outside the connector shell. This sealing ring, which in a cost effective embodiment comprises an O-ring, forms an additional barrier against the ingress of moisture into the interior of the connector shell. The barrier arranged within the formed part effected by the sealing ring can especially come into effect if the formed part has partly loosened from the cable covering owing to strong vibration of the connected equipment or owing to tight radii of curvature of the cable.
The formed part can preferably comprise a permanently elastic cast or injection moulded body of a suitable plastics material.
Advantageously, the connector shell, the multi-cornered part and/or the clamping sleeve comprise brass.